Permalinks £ sign

Hi

Im running 2.3.1 and all is working superbly except one little problem.

If my post contains the british ‘£’ sign, I get a 404 error

I.e. my post title reads

Slow Responses Cost £31 Billion!

The permanlink creates-

http://www.XXXXX.com/wordpress/2007/09/30/slow-responses-cost-%c2%a331-billion/

and in turn produces a 404 error

Is there anything I can do to rectify this?

Thanks in advance

Voddie